In a principal aspect the present invention relates to a clip construction for closure of packaging material and, more particularly, to a two-part clip construction wherein the components are preferably comprised of a polymeric material.
The use of metal and plastic clips that function as closures for bags and containers is well known. Many types of clips and/or straps are utilized to wrap or close the end of a bag or container. For example, metal clips may be formed about gathered bagging material as taught in U.S. Pat. No. 2,880,419 as well as U.S. Pat. No. 3,400,433. These patents, as well as U.S. Pat. No. 4,944,172 disclose generally U-shaped metal clips which are formed about gathered packing material by clip attachment machines. U.S. Pat. No. 4,528,898 is another patent showing a similar clip, as is U.S. Pat. No. 3,400,433. Various apparatus are used for attaching such clips about gathered casing material including apparatus as disclosed in U.S. Pat. Nos. 2,880,419 and 3,543,378 as well as U.S. Pat. Nos. 3,583,053 and 4,675,945.
Metal clips work quite well for closing and sealing gathered packaging material. However, the use of metal as a clip material has certain attributes which may not be desired. Thus, there has developed a series of products made from plastic or polymeric materials having that function as a closure. For example, Reissue U.S. Pat. No. 36,544 discloses a method and apparatus as well as a construction which employs a polymeric clip material comprised of a U-shaped clip member and a second gathering lock member which cooperates with the U-shaped member to hold a gathered neck of flexible packaging material in the closed condition. U.S. Pat. No. 4,275,485 discloses yet another construction comprised of a single hinged clamp or sealing device for holding gathered packaging materials closed. Similarly, U.S. Pat. No. 4,128,922 shows a two-part sealing device or clamp for closure of the neck of a bag material which has been gathered.
There are numerous additional examples of both metal and plastic polymeric clip constructions comprised of a single piece or member or more than one member. Nonetheless, there has remained a desire and need for an improved plastic clip construction.
Briefly, the present invention comprises a two-part clip construction including a first U-shaped clip member generally in the form of a staple having a crown which connects first and second spaced legs. The legs of each clip member are spaced a first uniform distance, and the ends of the legs are generally coterminous. A second element of the construction comprises a sealing block that includes a through passage between the opposite sides of the block. The opposite sides of the sealing block are spaced a lesser distance than the spacing of the clip member legs. The clip member legs are thus designed to fit over the opposite sides of the block and then be deformed or driven toward one another into the through passage that joins the opposite sides of the sealing block. The legs thus bend or plastically deform, extend into the through passage from opposite sides of the sealing block and are forced through the through passage from opposite sides of the sealing block. The legs are retained in their deformed condition by the interactive friction thereof with the through passage in the block. The legs are effectively locked to the sealing block even though the surfaces of the legs and through passage may be generally smooth, though one or both clip construction elements may be textured.
The sides of the block member through which the through passage is defined are, in the preferred embodiment, more closely spaced one from the other than the terminal ends of the legs of the U-shaped clip member. This enables the ends of the U-shaped clip member to fit over the opposite sides of the block, to then be deformed and pass through the through passage from the opposite sides of the sealing block.
In a preferred embodiment, a single through passage is utilized to engage, guide and maintain the leg ends in the appropriate position overlapping one another and side by side. However, the number of and cross sectional configuration of through passages is not considered to be a limiting feature of the invention. The sealing block itself, as well as the U-shaped clip, are preferably a polymeric material; however, other materials, including metal materials, may be used, in particular, for the clip. Nonetheless, the clip is preferably a polymeric material and may comprise a uniform cross section rod or a variable shaped cross section rod element. Again, the material may also be varied. Importantly, the material is generally plastic and deformable (i.e. plastic) and thus may be subjected to strain which forces the ends of the clip legs through the through passage of the block member.
The clip construction is capable of being utilized in clip attachment machinery which incorporates various modifications of existing prior art machinery thereby enabling use of the clip of the invention with modified prior art clip attachment equipment. More specifically, the U-shaped clip members are fed through a clip channel about gathered packing material. The gathered material is positioned between the clip legs adjacent the crown of the clip. The clip is then driven downwardly against an anvil in a manner which plastically deforms the legs directing them in opposite directions through the through passage of the block or leg locking member. The leg locking member is thus fitted in the anvil at the end of the channel which feeds U-shaped plastic clips thereto. The locking member is positioned on or in the anvil intermediate the pathway of the spaced legs of the U-shaped clip member that is driven down the clip channel. The anvil includes a separate guide slot for receiving each of the clip legs and for directing the legs substantially simultaneously in opposite directions through the through passage of the leg locking member. The top of the leg locking member or sealing block is positioned opposite the crown of the clip member and is preferably shaped in a fashion which will accentuate the sealing characteristics of the closure construction. For example, the top surface of the leg locking member may be arcuate or convex. It may also be partially convex with a center recess or it may include serrations or other design features which will enhance the holding capability of the clip closure construction. Thus, the clip construction of the invention which is comprised of two elements can be easily incorporated with and used with prior art clip attachment mechanisms modified in a manner which will enable attachment of the disclosed clip construction about gathered packaging material.
As a further feature of the invention, the legs of the clip member or clip element may incorporate serrations which will enhance the ability of the legs to engage or interlock when fitted through the through passage of the block member or block element. The cross sectional pattern of the legs and clip element may also be varied along the length of the clip to enhance assembly of the clip element and block element or member. The crown of the clip element may include lugs or other features which enable the clip elements to be nested.
Thus, it is an object of the invention to provide an improved clip construction.
It is a further object of the invention to provide an improved clip construction which may be incorporated with modified clip attachment mechanisms of the type generally utilized for packaging purposes for U-shaped metal clips.
Yet another object of the invention is to provide a two-part clip construction wherein a U-shaped plastic polymeric clip member is cooperative with and can engage a leg locking member or sealing block member by deformation of the legs of the clip member in opposite directions through a passage or passages in the leg locking member.
Yet a further object of the invention is to provide a two-part clip construction which may be manufactured from polymeric materials as well as non-polymeric materials, but which preferably can be made from polymeric materials.
Another object of the invention is to provide a cost effective, easily applied clip construction capable of being placed around gathered packaging material and retaining that gathered packaging material by closing and sealing the gathered packaging material.
Another object of the invention is to provide a closure made from a material, such as a polymeric material, that may pass through x-ray detection equipment without detection. This allows the producer of such packages to test for foreign metallic objects other than the clip.
These and other objects, advantages and features of the invention will be set forth in the detailed description which follows.